Process for treating hydrocarbons



- C. P. DUBBS lPROCESS Foa TREATING HYDRocARBoNs Filed May 24. 1924 Patented Aug. 25, 1925. i

UNITED STATES PATENT OFFICE.

CARBON P. DUBBS, OF WILMETTE, ILLINOIS, ASSIGNOR TO UNIVERSAL OIL PRODUCTS COMPANY, OF CHICAGO, ILLINO'IS, A CORPORATION OF SOUTH DAKOTA.

PROCESS FOR TREATING HYDROCARBONS.

Application filed May 24, 1924. Serial No. 715,632.

To @ZZ 107mm 'it may concern Be it known that I, CARBON I). DUBBs, a citizen of the United States, residing in the village of VVilmette, county of Cook, and State o-f Illinois, have invented certain new and useful Improvements in Processes for Treating Hydrocarbons, of which the following is a specification.

This invention relates to improvements in a process for converting hydrocarbon oils whereby maximum yields of low boiling point oils are obtained without the production of a substantial quality of liquid residuuin in the conversion chamber.

I have discovered that when oil is subjected to cracking conditions of heat and pressure, if it is mixed with a definiteI quantity of reflux condensate, that the volatile content of the oil on passing to an expansion or conversion chamber will undergo complete evaporation, separating into vapors and a. solid residue, without requiring the application of such excessive heat as to cause substantial deposition of carbon in the cracking tubes.

I have found in practice that in the use of a reflux conversion process such as broadly described in my Patent No. 1,392,629, that by increasing the quantity of reflux condensate admitted to the cracking coil with the raw charging stock, considerably above the quantity now generally cycled in the usual residuum runs, that the mixed oil passing through the cracking coil and entering the large conversion chamber will, under its own heat, separate into vapors and a substantially solid residue without so severely heating the oil as to deposit such quantities of carbon in the cracking tubes to coke the same, or cause destruction thereof. I am not fully aware as to why this reaction occurs during the treatment, but I do know that when temperatures and pressures are properly maintained, and a sufficient quantity of reiiux condensate is used in proportion to the raw oil, that substantially complete evaporation of the volatile content of the oil occurs without the formation of excessive carbon deposits in the heating zone, leaving in the expansion chamber only a residue of coke-like bodies largely free of liquid oil.

In the drawings, I have shown a side elevation of an apparatus capable of supporting this process.

Referring now more particularly to the drawing wherein like reference characters indicate corresponding parts, the numeral 1 designates a. furnace containing the heating coils 2 that are preferably of 4L diameter and of such a length as to represent approximately 1500 square feet of heating surface. This heating coil is fed by a charging line 3 introducing charging stock continuously thereto, consisting of a mixture of reflex condensate and raw oil. The charging stock passes through the cracking tubes 2 in a. continuously advancing stream, reaching a liquid transfer temperature of 850o F., more or less, and when at substantially this temperature, is delivered to the expansion or conversion chamber 7, which is a heavily insulated receptacle located outside of the zone of heat and approximately 10 feet in diameter and A15 feet in height. The transfer of oil occurs by means of the heavily insulated transfer line 5 in which there is positioned a valve 6 for a purpose to later appear. The chamber 7 is formed with top and bottom closures 8 and 9 respectively. These closures are removable to permit residue to be removed from the chamber. In the chamber 7 the volatile content of the oil admitted thereto substantially completely vaporizes. That is to say, the volatile content of the oil vaporizes leaving as a residue solid coke-like particles that accumulate in the chamber 7. This residue may contain some heavy liquid oil but it is an aim of the invention to, as far as possible, eliminate all such liquid oil and to keep the residue substantially free thereof. The vapors representing the bulk of the oil, pass out through the line 10, controlled by the. independently operable valve 11 and enter the lower end of the dephlegmator 12 for passage therethrough.

This dephlegmator can be of any well known construction. As shown, however, it is provided with a series of baffles or pans 13 to retard the passage of vapors therethrough, the uncondensed vapors from the dephlegmator passing through the line 16 controlled by the valve 17 into a final condenser 18, seated in a condenser box 19, the pressure distillate accumulating in the tank 20, having a gas discharge line controlled by a valve 21 by means of which a superatmospheric pressure may be maintained throughout the system. The distillate is discharged through either the line 23, or the line 24, continuously or intermittently. The temperature of the dephlegmator 12 is maintained sufficiently high so as to condense vapors, that have not been sufficiently cracked, by the cooling effect of pressure distillate introduced thereto by the pump 26 forcing the distillate through the pipe 27 having the manually controlled valve 28 therein, or in lieu of using pressure distillate as a cooling medium the charging stock admitted to the pump 4 may in part be passed through a line 18 by a proper control of the valve 14 and 152 and at the same time a portion of this charging stock is also admitted to the cracking coil through the line 8. In other words, the temperature of the dephlegmator may be controlled by the introduction of pressure distillate or charging stock thereto, or by a mixture of both. Substantial quantities of the vapors are condensed in the dephlegmator and this condensate drops down into the pressure leg 13b from which it is discharged to mix with the raw oil at the point X, the mixture of the two substances passing directly to the coil 2.

The expansion chamber 7 is shown as being provided with residual drawofl lines 29 controlled by the valves 30. These residual lines, however, remain closed during the normal operation of the process as no liquid residuum is drawn from this chamber after the process is in operation. This is because the residue remaining in the chamber 7 is substantially solid in nature as distinguished from the liquid residuum that is usually continuously discharged from an expansion chamber in conversion processes of this general character. Of course, a little liquid oil may collect from time to time in the chamber 7 in which event the oil can be withdrawn as necessary.

In describing briefly the process forming the subject matter of this invention, charging stock mixed with reflux condensate passes through the tube 2 where it is heated from 800O to 900O F. under ay superatmospheric pressure of say 120 pounds, and is admitted to the chamber 7. Either in the coil, or in the chamber, or in both, the oil separates into vapors, and a substantially solid coke-like residue, which accumulates in the chamber 7. The vapors which represent substantially the entire volatile content of the oil treated, discharge through the line 10 controlled by the valve 11 into a dephlegmator 12 which may be maintained at its discharge at a temperature of say 525O F., more or less, or such temperature as will cause the production of a desired pressure distillate and a sufiicient quantity of reflux condensate to enable the process to be carried out.

This temperature results in a substantial condensation of the vapors admitted to the dephlegmator, the reflux condensate dropping into the leg 13b and being returned by means of the line 14 with or Without a pressure pump, to the cracking coil with a relatively small quantity of raw charging stock passing through the line 3. The reflux condensate may approximate a temperature of say 7 00o F., more or less, while the vapors discharging from the dephlegmator may be of a temperature of say 525': F., but of course, these temperatures Will materially vary depending upon the character of the oil being treated as well as the products desired, and are only given as illustrations for some oils I have used. When an apparatus is being placed in operation and before operating conditions of temperature and pressure have been satisfactorily reached, and before the chamber has been sufliciently heated, the oil passed through the cracking tube and into the chamber 7 is withdrawn therefrom through the lines 29 and 30.

In carrying out my process, it may be desirable at timesk to maintain different pressures on various parts of the apparatus. For instance, a pressure of 120 pounds per square inch could be maintained on the coil 2 by controlling the valve 6, and a reduced pressure of pounds maintained on the chamber 7, dephlegmator 12 and condenser 13 by controlling the valve 21. It is also apparent that by controlling the valve 11, the chamber 7 could be maintained under a pressure above that maintained in the remaining portions of the apparatus. To increase the ruiming period of the apparatus, I may at times split the stream of heated oil passing from the coil and simultaneously admit different portions thereof to two or more expansion chambers 7 having independent dephlegmators and condensers.

To give an illustrative run of this nonresiduum process, I will first refer to the usual residuum run carried out in this apparatus in order to compare the differences in operation which must be followed to cause substantially complete vaporization of the oil in the expansion chamber without depositing excessive quantities of coke in the tubes. In the usual residuum run, that is, a run where residuum is continuously withdrawn from the chamber 7, I treated a topped Smackover crude of 17.7 degrees BaumeJ gravity, and during a period of thirteen hours in the apparatus just described, 17,240 gallons of this oil was treated. I obtained 9,520 gallons of pressure distillate of 50O Baume gravity. 32% of the raw charge treated represented liquid residuum and 13% gas and coke. The distillate thus obtained, represented 55% of the raw oil charge. During this run, I heated the oil to a liquid transfer temperature of approximately 890O F., while I maintained the temperature of the vapors leaving the dephleg; mator at approximately 5650 F., at the upper discharge end thereof. A pressure of 120 pounds per square inch was maintained during this run throughout the system.

As an illustrative run of the process herein described, I used the same oil, that is, a topped crude from the Smackover field of 17.7 degrees Baume gravity in the apparatus herein set forth. In a period of 13 hours, 1%,920 gallons of raw charging stock was passed through the cracking tubes 2. `With this oil, a large quantity of reflux condensate was also passed through the coil. I have been unable to ascertain the exact proportion of condensate to the charging stock that I admitted, but I do know that by maintaining the temperature of the reflux from the dephlegmator 12 at approximately 725D F., and in the desired quantity, the process described can be successfully carried out. The charging stock during passage through the cracking coil 2 was heated until its transfer temperature approximated 8950 F. The pressure maintained throughout the system during the run was 120 pounds per square inch. In the chamber 7 the heated oil separated entirely under its own heat into vapors representing approximately 80% of the charge, and a residue consisting of substantially solid colte-like bodies largely free of residual oil,

and of a non-fluid consistency. This residuel approximated 18% of the total oil charge,

2% of the oil treated representing incondensable gas. The vapors from the chamber 7 were passed through the line 10 and when discharged into the dephlegmator 12 were of a temperature of approximately 8200 F. The top exit temperature of the dephlegmator by introduction of pressure distillate through the line 27 or charging stock through the line 13 was lowered to a temperature of 500O F. immediately after the flow of liquid residue from the expansion chamber was discontinued, or in other words, at the time the plant was being transferred from a residuum run to a nonresiduum run. At this time it will be understood that the various parts of the apparatus had been sufficiently heated, and the treated oil had attained a temperature sufiicient to carry out the process. This low temperature in the dephlegmator resulted in a condensation of a most substantial quantity of the vapors admitted thereto. The condensate with the infed oil introduced to the top of the dephlegmator collected in the leg 13d, and as before stated was of a temperature approximately 725O F. AThe uncondensed vapors were continuously discharged from the dephlegm'ator and passed to the condenser 18, collecting as pressure distillate in the receiver 20. Approximately 12,200 gallons of pressure distillate were made during this run from the 14,920 gallons of charging stock, the distillate representing approximately 80% of the charging stock.

It will be understood that this sudden drop in the temperature of the dephlegmator results in an immediate production of increased ratio of reflux condensate to the charging oil passing to the heating coil. This additional quantity of condensate which is a low boiling point` oil results in the production of increased quantities of vapors in the expansion chamber after passage through the heating coil. These vapors on passing to the dephlegmator will again gradually raise the temperature of the dephlegmator to substantially or near its original point without decreasing the quantity of cooling oil fed to the top or the dephlegmater. At the saine time the same increased ratio of reflux condensate to the chargimq` oil is maintained in the cycle.

I am not familiar with the exact reaction that occurs in carrying out this process, but I believe that the complete distillation can perhaps be attributed to the relative large quantity of reflux that is used with the charging stock. This quantity of reflux is substantially greater than the quantity used in the usual residuum runs. I fully appreciate the result however,l that follows the operation of the process as described, and I have successfully treated the oil referred to by this process producing only vapors and a substantially solid residue that accumulates in the chamber 7.

By comparing the foregoing run with the usual residuum run, it will be seen that in the residuum run I fed substantially more charging stock than I did of thel non-residuum run, but mixed with this charging stock a substantially less quantity of reflux condensate. During these two runs, I maintained substantially the same furnace temperature, and the transfer temperature of the oil was approximately the same. In operating the non-residuum run however, and when switching the plant into this operation, I initially drop the temperature of the dephlegmator to approximately 500O F., which results in the formation of an increased quantity of reflux condensate to be continuously mixed with the charging stock of a decreased quantity. Naturally, with the lower temperature in the dephlegmator, I condense greater quantities of the vapors, and once having attained an operation where a greater proportion of condensate is admitted to the coil with the charging stock than use-d in the conventional residuum run, the increased quantities of vapors entering the dephlegmator due to the larger quantity of reflux condensate returned to the coil by the drop in the temperature of the dephlegmator gradually raises the temperature oi' the dephlegmator until the vapors leave at a temperature ot up to 5650 F. or at`any point desired depending upon the character ot' distillate the user of the process is seeking to obtain. rl`his rise in temperature, however, does not destroy the higher ratio ot reflux to the charging stock, as I have found that when this ratio is once obtained it will continue duringl the normal operations ot the plant even though the discharge temperature of the vapors of the dephlegmator will rise. However, should the quantity oi 'reflux fall below that necessary to accomplish the results set forth in this application, then I may intermittently drop the temperature of the dephlegmator until the desired quantity is produced.

In the operation just described, I found that when the transfer temperature of the oil approximated '8950, that it the deph'legmator temperature was dropped to 500O F., the retlux would collect in the leg in suiii cient quantities to support this process, and would approximate a temperature ot T250 F. The temperature ot the vapors issuing from the dephlegmator will gradually rise as increased quantity ot reflux condensate are admitted to the coil without decreasing the quantity of cooling oil admitted to the dephlegmator. This rise in temperature, however, does not destroy the ratio ot con-A densate to the charging` stock. However, in lbringing the process on stream, and as soon after the valves 30 in the drawoif line 29 are closed, and ust previous to the dropping of the temperature in the dep'hlegmator, some liquid oil may accumulate in the chamber 7. Such oil would accumulate because the expansion chamber is not sutiiciently heated, or because the oil is not at the desired transfer temperature. rfhis liquid oil however, is gradually evaporated during the non-residuum run by reason or heat units imparted thereto by the large quantity oi" incoming oil at a temperature higher than the temperature of the liquid oil accumulating in the chamber 7.

In the foregoing specification, Ighave clearly pointedV out and actually described certain commercial operations which I have performed with a given oil. Various other oils hawe also been treated by this process where slightly diiierent temperatures were used, but it is thought that the description ot the treatment ot one well known oil will suihce for the present purpose. In treating any oil, it is only necessary that vthe rei'lux condensate cycled with the charging stoel; beof a certain desirable temperature, and in certain definite quantities in excess oi the quantities now generally used in the residuum run. ll I-Iaving now described my invention, what I claim is:

l. A process for the conversion of hydrocarbon oil into lower boiling point hydrocarbon products, consisting in passing a stream ot' reflux condensate and charging oil through a heating tube where the mix* ture is heated to a cracking temperature without raising the temperature of the oil so high as tocause substantial deposition ot' carbon i'n the tube, passing the heated mixture Vfrom the tube to an enlarged reaction chamber where the oil mixture after passingk through the tube separates without any substantial rise in its temperature into vapors and a non-flowing carbon residue llargely free from residual oil and maintaining a superatmospheric pressure on the oil in said conduit and in said enlarged chamber, the ratio of the reflux condensate to the charging stock and the amount of heat supplied to the tubes being maintained sutiicient to cause the separation of the oil mixture into saidnon-iowing carbon residue and vapors in the reaction chamber.

2. A process i'or the conversion of hydrocarbon oil into lower boiling point hydro carbon products, consisting in mixing a distillate with a relatively heavier charging stock having a boiling point range substantially dili'ering from the boiling point range ot the distillate, in passing the mixed hydrocarbon substances .through a heating tube where a stream of such oil is heated to a cracking temperature without raising the temperature o'vf--the oil so high 'as to cause substantial deposition of carbon in the tube, in passing the heated mixture from the tube to an enlarged reaction chamber where the oil mixture separates without any substantial rise in its transfer temperature into vapors and a non-flowing carbon residue largely free from residual oil, and maintaining' a superatmospheric pressure on the oil in said tubeand in said enlarged chamber, the ratio of the distillate to the charging stock having the substantially different boiling point range and the amount of heat supplied to the oil stream passing through the tube being maintained suihcient to cause the separation of the oil mixture into said non-flowing carbon residue and vapors in the reaction chamber.

3. A process for the conversion of hydrocarbon oil into lower boiling point hydrocarbon products, consisting in mixing relatively light and heavier hydrocarbon oils, one having a boiling point range substantially dizering from the other, in passing the composite stream of oil through a heating tube where said stream is heated to a cracking temperature without raising the temperature of the oil so high as to cause a substantial deposition of carbon in the tube, passing the heated hydrocarbon material mixture from the tube to'an enlarged reaction chamber Where the hydrocarbon lllO material separates Without any substantial rise in its transfer temperature into vapors and a non-flowing carbon residue largely tree trom residual oil, in maintaining a superatmospheric pressure on the oil in said tube and in said enlarged chamber, and in controlling the ratio of the oil having one boiling point range to'the oil having the different boiling point range forming the composite charging stock and the amount ot tion of the oil mixture into said non-flowing carbon residue and vapors in the expansion chamber.

Il. A process for the conversion of hydrocarbon oil into lower boiling point hydrocarbon products, consisting in mixing a distillate thatl has once been subjected to a cracking'treatment with a charging oil that has not been subjected to such a treatment and which charging stock has'an end point substantially higher than the end point of free from residual oil, andv maintaining` a superatinospheric pressure on the oil in said tube and in said enlarged chamber, the ratio ot the distillate tothe charging oil and the amount ot heat applied to the tubes being maintained suii'icient to cause the separation of the oil mixture into said substantially non-Herring residue and vapors in the reaction chamber.

5. An oil conversion process, consisting in passing a stream of reflux condensate and charging oil through a heating .tube to be heated to a cracking temperature Without raising the temperature of the oil so high as to cause objectionable carbon depositionv in said tube, in transferring the heated hydrocarbon material after passing through the heating tube to an enlarged reaction chamber Where the oil separates Without any substantial rise in its transfer temperature into vapors and a non-flowing residue consisting of carbon substantially free from liquid residual oil, in subjecting the vapors to reiux condensation, `in maintaining a superatmospheric pressure on the oil in the heating tube and in the reaction chamber, the ratio of the reflux condensate to the charging oil being maintained such that under said conditions of heating in the tube the oil mixture separates Yin said reaction chamber into the non-flowing residue and vapors.

6. An oil conversion process, consisting in passing a stream of reflux condensate and charging oil through a heating tube to be heated to a cracking temperature Without. raising the temperature ot the oil so high as to cause objectionable carbon deposition in said tube, in transferring the heated hydrocarbon material after passing through the heating tube to an enlarged rei "action ychamber Where the oil separates Withlieat supplied to the tube tocause tlieyseparaout any substantial rise in its transfer tem- .;erature into vapors and a non-liloiving resi due consisting ot cai-bon substantially free `from liquid residual oil, in subjecting the vapors to reflux condensation, in maintaining a superatniosplieric pressure on the oil in the heating tube, the reaction chamber and the reliux condenser, the ratio of the reflux condensate to the charging oil being maintained such that under said conditions of heating in the tube the oil mixture separates in said reaction chamber into the nonlioiving residue and vapors.

7. An oil conversion process consisting in passing a composite stream of relatively light and heavier hydrocarbon oils through a heating tube Where the oil is subjected to a cracking temperature Without raising the temperature of the oil so high as to cause substantial deposition ot 'carbon in the tube, in transferring the heated hydrocarbon material to an enlarged Zone, in eltecting a separation oit the heated hydrocarbon material in said enlarged Zone into vapors and a substantially non-flowing carbon residue by controlling the composition of -the charging oil and the amount of heat applied to the heating tube, and in maintaining a superatmospheric pressure onthe oil undergoing treatment.

8. A process for the conversion of hydrocarbon oil into loive'r boiling point hydrocarbon products, consisting in mixing relatively light and heavier hydrocarbon oils, having dil'lerent boiling point ranges, in passing the composite stream of oil through a heating tube Where said stream is heated to a cracking temperature Without raising the temperature of the oil so high as to cause a substantial deposition ot carbon in the tube, passingthe heated -oil mixture from the tube to an enlarged reaction chamber Where the oil separates intovapors and a substantially non-Huid residue, in controlling the ratio of one ot .the oils to the other forming the composite charging stock and the amount of heat supplied to the tube to cause the separation of the oil mixture into'a substanundergoing conversion.

CARBON P. DUBBS. 

